First, exponential increase in technology/efficiency isn't necessary for the success of cryonics. Just positive increase, on average, provided the cryonics organizations can continue to exist and remain stable for a sufficiently long time.
Second, if people increase consumption that increases demand. When demand goes up, the marginal utility (usefulness, value, whatever you want to call it) for each additional unit goes up, which we can measure by the fact that they will purchase more at a given price. That in turn is what lets you move to larger scales which are more efficient (i.e. lower marginal cost). At some point the demand is met, the market saturated, and you can't move to higher scales.
But note that the development of new technology in general opens new possibilities for scaling up with less cost -- hence being profitable at lower marginal utility levels (i.e. sell at lower prices). Robotics for example are cheaper when computer processing power is cheaper, and when you have better ideas of which materials work best. This is true regardless of if the research is funded by people who want the technology for industrial robotics, people who want it for more efficient airplanes, or the government who wants it for military uses. Yet the existence of more efficient industrial robots means that a broad range of industries can now move to a higher scale cost-effectively.
The other way moving to larger scales can become profitable is when demand goes up. If a dozen smaller businesses collapse, a larger business can take their place at a higher efficiency. Or if the population doubles, the industry might respond by purchasing larger equipment.